PR summary

At today's new contributor meeting, a new contributor got a bit tripped up on instructions, so I:

• split the pyenv linux&mac/bat/powershell into tabs
• put the codespaces and local blurbs into a list to make 'em standout
• pushed the local install instructions into subheadings to restructure the index to try and making it clearer that local and github were equal but different options:
  

PR checklist

• "closes #0000" is in the body of the PR description tolink the related issue
• new and changed code istested
• Plotting related features are demonstrated in anexample
• New Features andAPI Changes are noted with adirective and release note
• Documentation complies withgeneral anddocstring guidelines